338 INSECT TRANSFORMATIONS. 



body, by bending itself into the form of a crescent ; 

 for if they were obstructed, whilst wet, they could not 

 afterwards be set to rights. 



All these changes are perfected, according to 

 Swammerdam, by the force of the circulating fluids 

 and the air, impelled by respiration, a fact of which, 

 we think, there cannot be any doubt. It is very 

 seldom, however, that we can surprise insects at the 

 precise moment of their transformation, as it is for 

 the most part very speedily accomplished, for the 

 whole of the preceding evolutions are usually com- 

 pleted in ten or fifteen minutes. " It happened by 

 mere chance," says Swammerdam, " that I observed 

 them for the first time : one of these vermicles ad- 

 hered to a stone wall in the river Loire, and it was 

 so softened by the water dashing up against it, that 

 it could only half perfect its change, so that I took it 

 partly free and partly yet fixed in the skin. I once 

 afterwards saw this change in the large kind of 

 dragon-fly {Mshna ? ) which had crept to land out of 

 a small lake, and cast its skin sitting in the grass." 



a, newly-hatched blow-fly magnified, showing the pulpy, 

 crumpled state of the whigs. b, the wings dry aud fully ex- 

 pa ndi-d. 



* Ribl, Nat., vol. i. p. 08. 



